In recent years, in view of portability of laptop computers, when accessing from a laptop computer to a network such as the Internet, it has become common to rely on network communication through radio communication such as wireless LAN which is convenient for moving around. Also, for connecting a laptop computer to external devices, radio data communication devices based on wireless LAN, Bluetooth, WWAN (wireless wide area network) are increasingly used when compared with those based on wired connection through USB or IEEE 1934.
Description of a conventional laptop computer will be given in the following.
FIG. 6A to FIG. 6C are appearance diagrams of a conventional laptop computer. In FIG. 6A, laptop computer 100 is composed of main body 101 and display 102 (such as LCD panel). And display 102 is provided with such function as a touch panel based on a pressure sensor or a digitizer. These functions perform a role equivalent to that of key board 103 and touch pad 104 as an input device. Here, as the inputting area specified by a dual-purpose display and touch panel is extremely narrow, it is more convenient to use ancillary thin pointed touch pen 105 as the inputting error is less.
Now, description of a conventional laptop computer configured as above will be given below.
As shown in FIG. 6A, a conventional laptop computer normally uses keyboard 103, mouse or touch pad 104 as an input device. Display 102 can not only be tilted backward and forward but it can also be turned by 180 degrees or more around axis of rotation 106 as shown in FIG. 6B. Accordingly, display 102 alone can be turned to a direction convenient to the user without moving main body 101 of the laptop computer. Furthermore, display 102 can be turned by 180 degrees around axis of rotation 106 and folded in a manner lapping over main body 101. As display 102 is equipped with a function of a touch panel, the laptop computer can be used as a tablet type computer as shown in FIG. 6C, and is superior in portability and high in convenience to the user.
FIG. 7A and FIG. 7B are diagrams showing a conventional laptop computer and radio communication antennas.
In FIG. 7A, laptop computer 100 is composed of laptop computer main body 101 and display 102 (such as LCD panel) as in FIG. 6A. Diversity antennas 71, 72 for radio communication are disposed at both ends of the upper part of display 102. Taking the effect of electromagnetic waves on the body of an operator of the laptop computer into consideration, care is taken to dispose antennas 71, 72 at locations as far away as possible from the operator.
As shown in FIG. 7B, diversity antennas 71, 72 for radio communication are simply composed of printed wiring board 31 prepared by printing copper foil on an insulator and cable 32 for transferring signals from a radio frequency signal sending section to a receiving section (not shown). In FIG. 7A, cabinet of the laptop computer is partially omitted. However, as the antennas are actually mounted inside the cabinet, they cannot be confirmed from outside. Here, diversity antenna is a system in which two or more antennas are connected and signal reception is made by switching as needed to the antenna with better reception. Accordingly, although two antennas 71, 72 are used in FIG. 7A, only one of them is used for actual reception.
For devices that generate electromagnetic waves, the value of specific absorption rate (SAR) is regulated. SAR value is a threshold determined based on scientific basis for preventing harmful effect of electromagnetic waves on human health. SAR value is a measure of absorption of electromagnetic waves by a living body and is referred to as “specific absorption ratio” or “local absorption ratio.” SAR value represents the amount of electromagnetic energy absorbed by an arbitrary organ in a fixed time when a living body is exposed to electromagnetic waves. Permissible value of SAR is different from country to country. To clear the permissible value, it is critically important to keep away human body as much as possible from a source of electromagnetic waves or to keep from touching one.
When a laptop computer is used in the mode depicted in FIG. 6A, the antennas for radio communication are located at right and left ends of an upper part of display 102. Assuming that an operator will sit in front of laptop computer main body 101 (at the position encircled by a dotted line in FIG. 6A) facing display 102, these locations have been determined in order that the antennas will be at a distance from the operator as much as possible. That is, in consideration of the effect of electromagnetic waves on the body of the operator, these locations are determined to be as far away as possible from the operator of the laptop computer.
However, when using a laptop computer as a tablet type computer as shown in FIG. 6C, as main body 101 and display 102 are folded together, the operator will have to directly hold main body 101 and display 102 in one hand. As a result, there is a high possibility that the hand or body will touch a portion close to the radio communication antennas located at both ends of display 102.
Technical content of the above is disclosed in Japanese Unexamined Patent Application Publication No. 2001-358802, Japanese Unexamined Patent Application Publication No. 2001-358514, Japanese Unexamined Patent Application Publication No. 2003-283393, Japanese Unexamined Patent Application Publication No. 2003-163956, and Japanese Unexamined Patent Application Publication No. 2002-290544.